Testing injecting drug users (IDUs) for HIV and hepatitis C virus (HCV) provides a useful opportunity for health promotion, risk-reduction assessment and counselling, and increases opportunities for treatment assessment, yet little is known about IDUs' experience of testing. This study aimed to examine the experiences of testing among IDUs recruited through primary healthcare and drug treatment services. Almost all the 229 participants recruited had been previously tested for HIV (96%) and HCV (97%), a median of five and four times respectively. Reasons for seeking testing were similar for both HIV and HCV, the most common being to protect others (72 and 74%, respectively), blood/needle exposure (66 and 70%, respectively) and to receive early treatment (66%, both). The most common locations for testing were general medical practices (GPs) (53%), specialised clinics (45%) and methadone clinics (43%). Preferred locations were similar for HIV and HCV testing: methadone clinics (47 and 48%, respectively), GPs (42%, both), specialised clinics (32%, both). The most common reasons for delaying testing were being anxious about waiting for results (66%), scared or afraid of finding out results (65%) and having trouble keeping appointments (64%). The majority of participants (HIV 62%; HCV 59%) reported that they would prefer pre-test counselling to be delivered in person rather than receiving written information and would prefer test results to be delivered face-to-face (HIV 83%; HCV 80%). High prevalence of testing suggests good uptake and high acceptability among this population in Australia. Specialised services for drug users such as methadone clinics and primary healthcare are suitable locations to provide access to testing.